1. Field of the Invention
This invention relates to orthopedic shoes, and more particularly to orthopedic shoes capable of lifting the tow section of the shoe when the shoe is in an unweighted state.
2. Description of the Prior Art
A person suffering from a condition known as "dropfoot" is unable to voluntarily pivot the foot around the ankle joint or to raise his toes while walking. Various types of prior art devices have attempted to mechanically produce the appropriate ankle rotation or toe lift.
U.S. Pat. No. 4,331,152 (Bartoli) discloses an orthopedic shoe having a flexible metal plate concealed between the various layers of the shoe sole. The rear end of the metal plate is connected by a link to a coiled spring deflection assembly positioned within a hollowed out chamber in the heel. The application of spring force to the plate erects the tip of the shoe with or without rotation.
U.S. Pat. No. 2,440,894 (Ceaser) discloses a spring-biased ankle rotation device having one end coupled to the calf of the wearer's leg and the opposing end coupled to the instep of the shoe. A spring positioned in the instep region of the shoe immediately in front of the heel causes rotation of the entire shoe about the wearer's ankle joint.
U.S. Pat. No. 3,585,993 (Heedly) discloses yet another device which rotates a wearer's foot about his ankle joint. This device includes a spring loaded axle positioned within a lateral passageway in the heel of the wearer's shoe. A first arm is coupled to the heel of the wearer's shoe and the second arm is coupled to the instep of the wearer's shoe. Unweighting of the shoe pivots the shoe around the wearer's ankle joint.
German Pat. Nos. 358,247 (Betz) and 397,582 (Brebeck) disclose other shoe-mounted devices for rotating a wearer's shoe around his ankle joint.